A magnetic random access memory (MRAM) is a type of a resistance change memories. As techniques for writing data to an MRAM, there have been known magnetic field writing and spin-transfer torque writing. Among these techniques, the spin-transfer torque writing has advantages in higher integration, lower power consumption, and higher performance because of the property of a spin-transfer torque device that a spin injection current is smaller in an amount necessary for magnetization reversal as magnetic bodies, become smaller in size.
Conventionally, a plurality of magnetic tunnel junction (MTJ) elements that share word lines are arranged respectively on different active areas and cell transistors are provided on both sides of each of the MTJ elements. When a certain MTJ element is accessed, two cell transistors provided on both sides of the MTJ element become conductive and then a current flows to the MTJ element. Because the gate width of one cell transistor is 2F (F is a Feature Size), the total, of the gate widths of the two cell transistors is 4F. Furthermore, the size of a memory cell is 12F2.
In order to write data to MTJ elements of the spin-transfer torque writing, a current larger than an inversion threshold current has to be supplied to the MTJ elements. In order to supply a current that is sufficiently higher than the inversion threshold current to the MTJ elements, a further increase of the gate width of the cell transistor has been desired.
Furthermore, in order to increase the gate width of the cell transistor, an active area having a large area is required; however, in manufacturing, it is difficult to separate the active area having a large area by small STIs (Shallow Trench Isolations).